Thermophysical modelling and parameter estimation of small solar system bodies via data assimilation
- Deriving thermophysical properties such as thermal inertia from thermal infrared observations provides useful insights into the structure of the surface material on planetary bodies. The estimation of these properties is usually done by fitting temperature variations calculated by thermophysical models to infrared observations. For multiple free model parameters, traditional methods such as least-squares fitting or Markov chain Monte Carlo methods become computationally too expensive. Consequently, the simultaneous estimation of several thermophysical parameters, together with their corresponding uncertainties and correlations, is often not computationally feasible and the analysis is usually reduced to fitting one or two parameters. Data assimilation (DA) methods have been shown to be robust while sufficiently accurate and computationally affordable even for a large number of parameters. This paper will introduce a standard sequential DA method, the ensemble square root filter, for thermophysical modelling of asteroid surfaces. ThisDeriving thermophysical properties such as thermal inertia from thermal infrared observations provides useful insights into the structure of the surface material on planetary bodies. The estimation of these properties is usually done by fitting temperature variations calculated by thermophysical models to infrared observations. For multiple free model parameters, traditional methods such as least-squares fitting or Markov chain Monte Carlo methods become computationally too expensive. Consequently, the simultaneous estimation of several thermophysical parameters, together with their corresponding uncertainties and correlations, is often not computationally feasible and the analysis is usually reduced to fitting one or two parameters. Data assimilation (DA) methods have been shown to be robust while sufficiently accurate and computationally affordable even for a large number of parameters. This paper will introduce a standard sequential DA method, the ensemble square root filter, for thermophysical modelling of asteroid surfaces. This method is used to re-analyse infrared observations of the MARA instrument, which measured the diurnal temperature variation of a single boulder on the surface of near-Earth asteroid (162173) Ryugu. The thermal inertia is estimated to be 295 +/- 18 Jm(-2) K-1 s(-1/2), while all five free parameters of the initial analysis are varied and estimated simultaneously. Based on this thermal inertia estimate the thermal conductivity of the boulder is estimated to be between 0.07 and 0.12,Wm(-1) K-1 and the porosity to be between 0.30 and 0.52. For the first time in thermophysical parameter derivation, correlations and uncertainties of all free model parameters are incorporated in the estimation procedure that is more than 5000 times more efficient than a comparable parameter sweep.…
Author details: | Maximilian HammORCiD, Ivanka PelivanORCiD, Matthias GrottORCiDGND, Jana de WiljesORCiDGND |
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DOI: | https://doi.org/10.1093/mnras/staa1755 |
ISSN: | 0035-8711 |
ISSN: | 1365-2966 |
Title of parent work (English): | Monthly notices of the Royal Astronomical Society |
Publisher: | Oxford Univ. Press |
Place of publishing: | Oxford |
Publication type: | Article |
Language: | English |
Date of first publication: | 2020/06/20 |
Publication year: | 2020 |
Release date: | 2022/11/10 |
Tag: | methods; methods: data analysis; minor planets, asteroids: individual: (162173) Ryugu; radiation mechanisms: thermal; statistical |
Volume: | 496 |
Issue: | 3 |
Number of pages: | 10 |
First page: | 2776 |
Last Page: | 2785 |
Funding institution: | Geo.X, the Research Network for Geosciences in Berlin and Potsdam; [SO_087_GeoX]; Deutsche Forschungsgemeinschaft (DFG)German Research; Foundation (DFG) [SFB1294/1, 318763901]; European Research Council; (ERC)European Research Council (ERC) [339390]; Simons CRM; Scholar-in-Residence Program |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Mathematik |
DDC classification: | 5 Naturwissenschaften und Mathematik / 51 Mathematik / 510 Mathematik |
Peer review: | Referiert |
Publishing method: | Open Access / Hybrid Open-Access |
License (German): | CC-BY - Namensnennung 4.0 International |